Nickel-base casting superalloy and cast component for stream turbine using the same as material

Abstract

A Ni-base casting superalloy containing, in masse, C: 0.05 to 0.2, Si: 0.01 to 1, Mn: 0.01 to 1, Co: 5 to 20, Fe: 10 or less, Cr: 15 to 25, and one kind or two kinds or more of Mo, W, and Re, with Mo+(W+Re)/2: 8 to 25, the balance being Ni and unavoidable impurities.

What is claimed is: 
     
       1. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, and 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5. 
 
     
     
       2. The nickel-base casting superalloy according to  claim 1 , wherein a content of one kind or two kinds of said niobium (Nb) and tantalum (Ta) is Nb +Ta/2=1.0 to 2.5 in mass %. 
     
     
       3. The nickel-base casting superalloy according to  claim 1 , which exhibits a creep rupture time, measured at 700° C. at 250 MPa, of from 1397.5 to 2623.7 hours and which exhibits a creep rupture elongation percentage, measured at 700° C. at 250 MPa, of from 9.3 to 16.1%. 
     
     
       4. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 aluminum (Al): 0.1 to 0.4, 
 titanium (Ti): 0.1 to 2.5, and 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5, 
 the balance being nickel (Ni) and unavoidable impurities. 
 
     
     
       5. The nickel-base casting superalloy according to  claim 4 , wherein a content of said aluminum (Al) is 0.2 to 0.3 in mass %. 
     
     
       6. The nickel-base casting superalloy according to  claim 4 , wherein a content of said titanium (Ti) is 0.5 to 2.0 in mass %. 
     
     
       7. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 7 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5, and boron (B): 0.001 to 0.02. 
 
     
     
       8. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5, and zirconium (Zr): 0.01 to 0.2. 
 
     
     
       9. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 aluminum (Al): 0.1 to 0.4, 
 titanium (Ti): 0.1 to 2.5, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5, and 
 boron (B): 0.001 to 0.02. 
 
     
     
       10. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 aluminum (Al): 0.1 to 0.4, 
 titanium (Ti): 0.1 to 2.5, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 0.5 to 5, and 
 zirconium (Zr): 0.01 to 0.2. 
 
     
     
       11. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/ 2: 20.5 to 25, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/ 2: 0.5 to 5, 
 boron (B): 0.001 to 0.02, and 
 zirconium (Zr): 0.01 to 0.2. 
 
     
     
       12. A nickel-base casting superalloy comprising, in mass %,
 nickel, 
 carbon (C): 0.05 to 0.2, 
 silicon (Si): 0.01 to 1, 
 manganese (Mn): 0.01 to 1, 
 cobalt (Co): 13 to 17, 
 iron (Fe): 5.3 or less, 
 chromium (Cr): 15 to 25, 
 molybdenum (Mo): 12.8 to 17.4, and at least one of tungsten (W) and rhenium (Re), provided that the total amount of molybdenum, tungsten, and rhenium satisfies: Mo +(W +Re)/2: 20.5 to 25, 
 aluminum (Al): 0.1 to 0.4, 
 titanium (Ti): 0.1 to 2.5, 
 one kind or two kinds of niobium (Nb) and tantalum (Ta), with Nb +Ta/2: 1 to 5, 
 boron (B): 0.001 to 0.02, and 
 zirconium (Zr): 0.01 to 0.2. 
 
     
     
       13. The nickel-base casting superalloy according to any one of  claims 1 ,  4 ,  7 ,  8 ,  9 ,  10 ,  11 , and  12 , being applied to a cast component of a steam turbine. 
     
     
       14. A cast component for a steam turbine of a steam turbine plant to which a high-temperature steam is introduced, the cast component being at least partly made of the nickel-base casting superalloy according to any one of  claims 1 ,  4 ,  7 ,  8 ,  9 ,  10 ,  11 , and  12 .